Genetics and Breast Cancer


About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child. But before we get to specifics, let’s start with some basics on breast cancer and genetics. And if you have more questions, contact our Client Services Coordinator, Janet Dees, at (205) 990-5367 or [email protected]. She can help you get in touch with an expert. Si hablas español y quieres más información, por favor contacta a Yadira Robayna, al (205) 990-5375 O al [email protected].


What is genetics? 

This is how we study and describe the genes in our bodies. Genes carry information and determine traits like what you look like, including your eye color, hair type, and smile. Some illnesses, like cancer, can be caused by genes that are not working correctly. When we talk about genetics, we explain them as hereditary, or passing down physical or mental characteristics from one generation to another.

According to the American Cancer Society, 1 in 8 women will develop breast cancer in their lifetime. How do you know how likely you are to be that one? It may help to consider the different categories of breast cancer and how genetics can help you understand your risk.


Sporadic Breast Cancer

  • It is the most common type of breast cancer and happens due to getting older, hormones, and chance. About 65% of cancers are considered sporadic.
  • Sporadic breast cancers typically happen at later ages and in women without family history.
  • Having a family history of sporadic breast cancer is unlikely to change your risk of breast cancer.


Familial Breast Cancer

  • This happens when sporadic factors, like your age, hormones, and lifestyle, combine with multiple genetic factors shared within families. About 15-25% of cancers are considered familial.
  • In families with this type of breast cancer, more women on one side of the family develop breast cancer than we would expect by chance. These diagnoses may happen later in life.
  • Having a family history of cancer does not mean you or your family have a hereditary condition that causes breast cancer.
  • If you have a family history of familial breast cancer, you may be at higher risk than the average woman to develop breast cancer.


Hereditary Breast Cancer

  • This occurs when there is a single cause for breast cancer that is passed down through a family. This means that individuals are born with a hereditary condition that makes it more likely to have breast cancer and potentially other cancers. About 5-10% of cancers are considered hereditary.
  • In families with hereditary breast cancer, we may see breast cancer before menopause, several family members with breast or other related cancers, individuals that have been diagnosed with more than one cancer, and uncommon cancer diagnoses, like male breast cancer.
  • Ethnic background can also play a role because there are certain hereditary conditions that are more common in some groups than others.
  • If you have a family history of a hereditary condition that makes it more likely for individuals to get breast cancer and you have been found to have that condition, you may be at a relatively high risk to develop breast cancer in your lifetime.

It may be helpful to see a genetic counselor if you have a personal or family history of cancer. A genetic counselor can look at your medical and family history and determine if genetic testing is right for you. If hereditary cancer is suspected, genetic testing may be helpful.


What is genetic testing?

Genetic testing starts with a blood or saliva (spit) sample from an individual. The sample is sent off to a lab that “sequences the DNA” to see if there is a genetic mutation or change in someone’s DNA. Genetic testing technology has evolved rapidly, and a genetic counselor can determine whether an individual meets testing criteria, find the best person in the family to test, and discuss the pros and cons of genetic testing options.


What is genetic counseling?

After testing, a genetic counselor works with the individual to review the results and discuss next steps according to National Comprehensive Cancer Network (NCCN) guidelines. This may include more cancer screenings or lifestyle changes to reduce your cancer risk. No changes should be made without talking with your physician.


How can I get genetic testing?

Individuals who have been referred to a genetic counselor for testing or are interested in having testing must meet certain criteria for testing. This includes:

  • Being diagnosed with cancer at a young age (50 years old or younger)
  • Having 1 or more family members with cancer relating to a specific syndrome, such as hereditary breast and ovarian cancer (HBOC), a single family member diagnosed with multiple cancers (such as two breast cancer diagnoses) or a family member diagnosed with a rare cancer (such as ovarian or pancreatic)

If you are interested in genetic testing and do not know where to start, talk with your doctors, such as your oncologist, primary care physician or OBGYN about your interest. It is important to know about your family’s history of cancer on your mother and father’s sides of the family. This includes types of cancer(s), age of family members when diagnosed, if metastatic (cancer spread to another part of the body), and if the individual was diagnosed with more than one type of cancer. Let your physician know about your family history to determine if you should talk with a genetic counselor.

Having genetic testing done can be scary, but having the knowledge and understanding of your unique genetic makeup may provide answers and help with cancer screenings and treatment plans for you and your family.


Useful Videos:

Cancer Conversation: Cancer and Genetics

Forge Coffee Conversation: Breast Cancer & Genetic Testing


This information is shared by Forge partner and High Risk Counselor, Aundriano Capers, who works with patients who are at high risk for hereditary cancer at St. Vincent’s Bruno Cancer Center in Birmingham, AL.